Conventional microtomes for producing thin tissue sections are as a rule equipped with an eccentric drive, which sets a blade in a horizontal oscillation. By means of a feed device, the oscillating blade is passed through an object to be processed, fresh tissue for example, so that the desired section of the object is severed. The use of eccentric drives is bound up with a number of drawbacks. The oscillation frequency of the blade is limited, because with the eccentric drive the masses of a knife holder and guides also have to be accelerated. Furthermore, the oscillation amplitude of the blade is also restricted by the eccentric itself to around 1 mm as a rule. An essential drawback in the production of precision sections of biological materials is caused by the formation of vertical movements (vertical beats), which diverge from the horizontal oscillation direction of the blade. The eccentric drive generates a vertical beat at its reversal points. Furthermore, the tendency towards vertical oscillation increases at higher oscillation frequencies, at which the effective forces increase. As a result of the vertical oscillations, the tissue to be processed is separated not only in the feed direction. Cells in the tissue surface are also damaged. This makes the subsequent examination of the tissue section more difficult.
In a modified design of a microtome, such as is commercially available for example under the name “Vibracut 3”, manufacturer: FTB Feinwerktechnik, the knife holder is caused to oscillate with a moving lift magnet. This form of drive is disadvantageous, since the vibration frequency of the blade is tied to the resonance frequency of the knife holder. Furthermore, it is in turn not possible to rule out vertical oscillations to the extent required for precision applications, especially in microbiology and neurology.
The stated problems with the vibrational drive of a microtome blade also arise with other precision tools and manipulators with which a linear oscillatory motion in a predetermined oscillation direction is desired, whilst in all other directions no deflection movements take place. This concerns, for example, tools for the processing of micro-systems or micro-surgical instruments.
It would accordingly be advantageous to provide an improved drive device for generating vibrations, with which the drawbacks of the conventional drives for precision tools or manipulators are overcome and which in particular enables a generation of vibrations in a predetermined oscillation direction with an adjustable oscillation frequency and oscillation amplitude and without lateral deflections. It would also be advantageous to provide an improved microtome, with which the thickness of tissue sections can be reduced and the damage to tissue parts outside in the sectioning direction can be reduced.